Related Experiment Videos

Genetic cooperation between p21Cip1 and INK4 inhibitors in cellular senescence and tumor suppression

V Quereda1, J Martinalbo, P Dubus

  • 1Cell Division and Cancer Group, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain.

Oncogene
|June 30, 2007
PubMed

Insights

Cell-cycle inhibitors p21(Cip1) and INK4 pathways cooperate to suppress cellular senescence and tumor formation. Inactivating both pathways leads to immortal cells and increased sarcoma incidence in mice.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • Cell-cycle inhibitors of the Cip/Kip and INK4 families are crucial for cellular senescence and tumor suppression.
  • Proteins like p21(Cip1), p16(INK4a), and p15(INK4b) are coexpressed during antiproliferative signaling, leading to cell-cycle arrest.
  • Understanding the synergistic roles of these inhibitors is key to comprehending senescence and cancer development.

Purpose of the Study:

  • To investigate the cooperative roles of p21(Cip1) and INK4 pathways in cellular senescence and tumor suppression.
  • To characterize the growth and senescence behavior of primary cells deficient in p21(Cip1) and expressing an INK4-insensitive Cdk4(R24C) mutant.
  • To assess the in vivo tumor suppressive functions of combined p21(Cip1) and INK4 pathway inactivation.

Main Methods:

  • Generated primary cells deficient in p21(Cip1) and expressing a mutant Cdk4(R24C) (cyclin-dependent kinase) insensitive to INK4 proteins.
  • Analyzed the growth properties and senescent behavior of these double mutant cells in vitro.
  • Studied tumor incidence in mice with combined inactivation of INK4 and p21(Cip1) pathways (Cdk4(R24C); p21(Cip1)-null mice).

Main Results:

  • Inactivation of both p21(Cip1) and INK4 pathways strongly cooperated to suppress cellular senescence in vitro.
  • Double mutant cells exhibited immortal growth and increased sensitivity to oncogene-induced cellular transformation.
  • Double mutant mice showed a higher incidence of specific sarcomas, indicating in vivo cooperation.

Conclusions:

  • The p21(Cip1) and INK4 families of cell-cycle inhibitors cooperate significantly in regulating cellular senescence.
  • Combined inactivation of these pathways promotes cellular immortalization and oncogenic transformation.
  • These findings highlight a critical cooperative role in tumor suppression, suggesting therapeutic potential.

Related Concept Videos

Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Inhibition of CDK Activity02:34

Inhibition of CDK Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
Cancer-Critical Genes II: Tumor Suppressor Genes01:05

Cancer-Critical Genes II: Tumor Suppressor Genes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
Cancer-Critical Genes II: Tumor Suppressor Genes01:05

Cancer-Critical Genes II: Tumor Suppressor Genes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.